IS ANTIFUNGAL SUSCEPTIBILITY TESTING USEFUL IN GUIDING FLUCONAZOLE THERAPY

Recently, the National Committee for Clinical Laboratory Standards (NC CLS) subcommittee on antifungal susceptibility testing published a pro posed standard for a broth macrodilution method for in vitro susceptib ility testing of yeasts, The major reason for developing such a method is to predict the likely clinical and microbiological outcome of trea tment. A number of studies of fluconazole have attempted to correlate in vitro minimum inhibitory concentrations (MICs) with in vivo efficac y in humans by means of a variety of methods, including the NCCLS prop osed standard, These studies have clearly demonstrated that the abilit y to predict clinical outcome with MICs is dependent on the patient po pulation studied, Thus, fluconazole MICs were correlated with clinical outcomes for patients with AIDS-associated oropharyngeal candidiasis. In contrast, fluconazole MICs did not correlate with clinical outcome s for patients with candidemia who did not have AIDS; these patients h ave numerous factors that can independently influence the response to antifungal therapy aside from the MIC. Data on patients with AIDS-asso ciated cryptococcal meningitis from my laboratory demonstrated that th e use of fluconazole MICs in conjunction with clinical variables, such as blood culture results, enhances the ability to predict treatment o utcome. More investigations addressing the role of host factors in the in vitro-in vivo correlation are necessary before antifungal testing can be useful in guiding therapy.